Podcast generation failed twice at the audio stage, for two unrelated reasons
that look similar from the UI but need opposite fixes.
1) TTS/STT ran as nohup background processes and silently did not survive a
reboot. Podcasts then failed with "Failed to generate speech: All connection
attempts failed" (httpx.ConnectError) even though outline and transcript had
generated fine.
Both now run as systemd user units. The unit files are versioned in
services/systemd/ (using %h, not a hardcoded home) and installed by
scripts/start_services.sh, which also enables linger so they start on boot
without a login session. They pin GPU 2 by UUID, not by index: CUDA orders
devices "fastest first", so index 2 can resolve to the T600.
2) GPU 2 is shared by three processes (TTS, STT and the separate chatterbox-tts
MCP service on :9999), leaving ~12 GB of headroom. podcast_creator sends
TTS_BATCH_SIZE (default 5) clips concurrently, and since /audio/speech is a
sync FastAPI handler, they generated genuinely in parallel on one shared
model. Activation memory multiplied, the TTS process hit 16.7 GB and threw
torch.OutOfMemoryError, surfacing as "HTTP 500" from the endpoint.
tts_server.py now serializes generation behind a lock (GPU-bound work, so
parallelism buys no throughput — it only multiplies peak VRAM) and frees the
cache afterwards. TTS_BATCH_SIZE=1 keeps the client from queuing requests in
that lock and running into esperanto's 300s TTS timeout; ESPERANTO_TTS_TIMEOUT
is raised to 600s as headroom.
Verified: 5 concurrent /audio/speech requests all return 200 with GPU 2 peaking
at ~11.5 GB (was 16.7 GB for the TTS process alone), and the previously failed
episode now completes end to end — 38/38 batches, 10:56 min of audio, zero OOM.
Docs record both failure signatures side by side, since ConnectError (server
dead) and HTTP 500 (server alive, out of VRAM) have very different remedies.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
tts_server.py now resolves `voice` against services/voices/*.wav (gitignored,
personal recordings) and clones via chatterbox's audio_prompt_path, falling
back to "default" (symlinked to ~/chatterbox-tts-cli/my_voice_deutsch_60s.wav)
for unknown names, or to the old built-in-voice-by-language-code behavior if
`voice` is a recognized language. All podcast speaker profiles now point at
voice_id "default" until distinct per-speaker reference clips are added.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Wraps the locally installed chatterbox-tts and faster-whisper packages in thin
FastAPI servers implementing OpenAI's audio API shape, since neither Ollama nor
OpenRouter support speech. Pinned to GPU 2 to avoid contending with Ollama's
resident models on GPU 1. Requires UFW rules for 8901/8902 (same pattern as
the existing 11434 rule) since UFW defaults to deny-incoming.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
